Positive displacement slipper pump with flangeless drive shaft



Dec. 22, 1970 D. E. NICHOLS ETA!- ,5 3

POSITIVE DISPLACEMENT SLIPPER PUMP WITH FLANGELESS DRIVE SHAFT Filed March 5, 1969 5 Sheets-$11881: 1

Dec. 22, 1970 3,549,288

POSITIVE DISPLACEMENT SLIPPER PUMP WITH FLANGELESS DRIVE SHAFT D. E. NICHOLS A!- 5 Sheets-Sheet '1:

Filed. March 5, 1969 d0///V.h/000 672 Dec. 22, 1970 l s ETAL 3,54 9',-288,,

POSITIVE DISPLACEMENT SLIPPER PUMP WITH FLANGBLES$ DRIVE SHAFT Filed March 5. 1969 5 Sheets-Sheet 3 I 70 74 36 1 /Z I34 2 30 nvva/mai- I g 3 .oawarz/wc/ra 6. I 1 8r, uo/m/ c2 M090 Dec. 22, I970 o. E. NlCHOLS ETAL 3,549,288

POSITIVE DISPLACEMENT SLIPPER PUMP WITH FLANGELESSIDRIVE sHAfiT 5 Sheets-Sheet 4 Filed March 5, 1969 JOIY/V 5- M000 Dec. 22, 1970 D. E. NICHOLS ErAL 3,549,288

POSITIVE DISPLACEMENT SLIPPER PUMP WITH FLANGELE SS DRIVE SHAFT Filed March 5, 1969 5 Sheets-Shet P rr m erj.

United States Patent 3,549,288 POSITIVE DISPLACEMENT SLIPPER PUMP WITH FLANGELESS DRIVE SHAFT Denver E. Nichols, Walled Lake, and John E. Wood, Detroit, Mich, assignors to Ford Motor Company,

Dearborn, Mich., a corporation of Delaware Filed Mar. 5, 1969, Ser. No. 804,592

Int. Cl. F04c 1/00 US. Cl. 418-133 8 Claims ABSTRACT OF THE DISCLOSURE A positive displacement slipper pump comprising a rotor having arcuately spaced recesses with slippers mounted therein, a cam surrounding said rotor against which the slippers are slidably engaged, a drive shaft splined to the rotor, and a pressure plate registering with a pilot groove formed in said drive shaft, said pressure plate being eccentrically positioned with respect to the axis of the shaft thereby permitting registry between the shaft and the groove to prevent axial displacement of the shaft with respect to the rotor.

GENERAL DESCRIPTION OF THE INVENTION Our invention relates to improvements in positive displacement pumps. It is adapted especially to be used with positive displacement slipper pumps, but it is capable of being used also with vane-type pumps. In each instance the pump would include a rotor operating in a pump housing which defines a cam surface surrounding the rotor. The slippers or the vanes would be carried by the rotor in sliding engagement with the cam surface.

The slippers or vanes define pumping chambers which accommodate the oil displaced from an inlet port to an outlet port. Pressure plates located on either side of the rotor register with the rotor to define the axial extent of the pumping chambers. They also provide appropriate porting for distributing pressure from the inlet to the outlet of the pump.

The rotor is formed with an internally splined opening in which an externally splined portion of the drive shaft is received.

In one commercially available power steering pump for use in automotive vehicle chassis assemblies, a drive shaft is provided with a thrust shoulder by means of a forging operation. After the forging operation is completed, the shaft must be turned to provide the necessary axial tolerances. 'Ihe thrust forces acting on the pump assembly and on the shaft are distributed through the shoulder and into the fixed pump housing. If the thrust forces are reversed, they are distributed from the shaft to an end plate or upper pressure plate.

In our improved construction thrust forces are accommodated without the necessity for providing the usual thrust shoulders on the drive shaft. There is no necessity, furthermore, to extend the shaft beyond the splined connection between the shaft and the rotor, as in the usual case, since provision is made for distributing reaction forces from the drive shaft to the housing regardless of the direction of the forces acting on the drive shaft. This reduces the amount of material required, and the drive shaft itself can be formed by means of a simple centerless grinding operation. No additional thrust distributing parts such as snap rings or thrust collars are required.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS FIG. 1 shows in cross-sectional form a pump assembly embodying the improvements of our invention.

FIG. 2 is an exploded assembly view showing in spatial relationship the elements of the FIG. 1 assembly.

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FIG. 3 is a partial cross-sectional view taken along the plane of section line 3-3 of FIG. 1.

FIG. 4 shows a detail view in side elevation of the lower pressure plate which registers with the drive shaft.

FIG. 5 is a detail view of the drive shaft used in the FIG. 1 assembly.

FIG. 6 is a sub-assembly view showing the rotor body slsgmlaly as seen from the plane of section line 6-6 of PARTICULAR DESCRIPTION OF THE INVENTION In FIG. 1 and in FIG. 2 numeral 10 designates a portion of the pump housing. The pump body or cam 12 is secured in place adjacent the housing 10, and end plates or pressure plates 14 and 16 are situated on either side of the cam 12. A ported valve plate 18 engages the lefthand surface of the pressure plate 16, and it in turn is held in place yieldably by compression springs 20. These are anchored on one end of the pump cover 22 which surrounds the pump assembly. Cover 22 is provided with an end flange 24 at its right-hand end, which is bolted by means of bolts 26 to the housing 10. The pressure plates 14 and 16 and the cam 12, as well as the plate 18, are held in proper registry by means of guide pins 28.

A rotor 30 is positioned within the cam or housing 12 as best seen in FIG. 6. It includes angularly spaced blade openings 32. A separate slipper or blade 34 is situated in each opening 32, and it is urged radially outwardly by a slipper spring such as that shown at 36 in FIG. 1. The slippers engage slidably the internal cam surface 38 of the cam or housing 12.

An O-ring 40 surrounds the plate 18 and is arranged in sealing engagement with the inner surface of the cover or housing portion 22. Plate 18 is adapted to accommodate the flow control and pressure limiting valving, and it is accordingly identified as a valve plate. The region within the cover 22 on the left-hand side of the valve plate 18 serves as a high pressuer chamber. This chamber is identified in FIG. 1 by reference character 48. A fluid outlet passage 50 formed in a fitting 52 communicates with the chamber 48. A sheet metal case 54 surrounds the cover for housing 22 and it serves as a fluid reservoir.

Lower pressure plate '14 is provided with inlet ports 56 and 58. These permit fluid communication between low pressure inlet region 60 and the pumping chamber situated between the cam surface 38 and the rotor. Region 60 is sealed or isolated from the chamber 48 by the O ring 46. The fluid in the reservoir defined by case 54 communicates directly with the region 60.

The pressure plate 14 also is provided with high pressure outlet ports 62 and 64 which communicate with the chamber 48 through suitable internal passage structure formed in the upper pressure plate 16 and the valve plate 18.

A drive shaft 66 extends through opening 68 in the housing 10. It is splined at 70 to permit a splined connection with internal splines 72 formed in a central open ing of the rotor 30.

The pressure plate 14 is provided with a central opening 76 having a center that is positioned eccentrically with respect to the center of the shaft 66. The eccentricity is indicated in FIG. 4 by the reference legend E.

Shaft 66 is provided with a groove 78 which is adapted to receive one edge of the opening 76 of the plate 14. The side surfaces 80 and 82 of the groove 78 are adapted to engage the opposite sides of the plate 14 thereby preventing shifting movement of the shaft 66.

There is no need in this arrangement to provide a thrust washer for accommodating thrust transfer between the shaft 66 and the pressure plate 16. Neither is there any need to provide a snap ring abutment or other connection between the shaft '66 and rotor 30.

Having thus described a preferred form of our-invention, what we claim and desire to secure by United States Letters Patent is:

1. A positive displacement pump comprising a cam housing, a pump rotor situated in said housing and cooperating therewith to define fluid pumping chambers, a

pump housing surrounding said cam housing, a pressure plate situated on each side of said cam housing and cooperating with said rotor to partly define said pumping chambers, porting in said pressure plates including a low pressure port extending to a low pressure region of said pump and a high pressure port extending to a high pressure region of said pump, pumping elements carried by said rotor on its periphery and adapted to move fluid from said low pressure port through a pumping arc to said high pressure port, a drive shaft, a central opening in said rotor, one end of said drive shaft extending into said central opening and being mechanically connected to said rotor, an annular groove formed in said drive shaft adjacent said rotor, an eccentric opening formed in one of said pressure plates through which said drive shaft extends, one margin of said eccentric opening registering with said annular groove thereby accommodating axial thrust forces on said shaft in either direction.

2. The combination as set forth in claim 1 wherein said one pressure plate is located between said pump housing and said cam housing and arranged generally in the plane in which said annular groove in said drive shaft is positioned when said drive shaft is assembled with its one end in said rotor opening.

3. The combination as set forth in claim lwherein said housing comprises a high pressure chamber located on one side of said other pressure plate, said one end of said drive shaft being splined to said rotor, said one end of said drive shaft being axially spaced from the other pressure plate.

4. The combination as set forth in claim 2 wherein said housing comprises a high pressure chamber located on one side of said other pressure plate, said one end of said drive shaft being splined to said rotor,said one end of said drive shaft being axially spaced from the other pressure plate.

-5. The combination as set forth in claim 1 wherein one mangin of said opening in said one pressure plate extends within said annular groove whereby one side of said annular groove overlies one side of said pressure plate overian area having generally the shape of a crescent, said crescent-shaped area defining a bearing surface that accommodates axial thrust forces acting on said drive shaft.

6. The combination as set forth in claim 2 wherein one margin of said opening in said one pressure plate extends within said annular groove whereby one side of said annular groove overlies one side of said pressure plate over an area having generally the shape of a crescent, said crescent-shaped area defining a bearing surface that agcommodates axial thrust forces acting on said drive s aft.

7. The combination as set forth in claim 3 wherein one margin of said opening in said one pressure plate extends within said annular groove whereby one side of said annular groove overlies one side of said pressure plate over an area having generally the shape of a crescent, said crescent-shaped area defining a bearing surface that accommodates axial thrust forces acting on said drive shaft.

' 8.'The combination as set forth in claim 4 wherein one margin of said opening in said one pressure plate extends within said annular groove whereby one side of said annular groove overlies one side of said pressure plate over an area having generally the shap of a cres- 3/ 1958 Crane 103-161 9/1966 Clark et a1. 103-13'6X ROBERT M. WALKER, Primary Examiner US. Cl. X.-R. 41-8-82 

